1. Technical Field
The present invention relates generally to a display system using a plurality of graphics adapters and, more particularly to an image display device adopting an image dividing method which demonstrates excellent performance and great flexibility.
2. Description of the Related Art
A high resolution display which showed a slow progress with respect to a CRT display has been making rapid progress with introductions of new technologies such as liquid crystal liquid. To be more specific, the liquid crystal display (LCD) can achieve a high resolution more easily compared to the CRT display by microfabricating it. With respect to this LCD, high definition (ultra-high resolution) displays with a very high resolution such as QXGA (Quad Extended Graphics Array) (2048xc3x971536 dots), QSXGA (Quad Super Extended Graphics Array) (2560xc3x972048 dots), and QUXGA (Quad Ultra Extended Graphics Array) (3200xc3x972400 dots) have been put to practical use by making a panel itself into a high definition one.
On the other hand, a device called a graphics adapter for performing image creation and the like to display an image on a display is provided in a personal computer (PC). A memory for writing and storing the image to be displayed on the display is provided in the graphics adapter, and this memory is called a frame buffer.
As a technique for performing a high resolution display, there has been one to divide a screen to display an image using a plurality of graphics adapters. Specifically, this technique has a feature in that instead of developing a special graphics adapter having a large frame buffer, using an ordinary graphic adapters, a screen is divided into two to four sections, one graphics adapter is assigned to the corresponding section, and a corresponding image is displayed. These techniques are generally called xe2x80x98Partitioning Methodxe2x80x99 or xe2x80x98Tiling Method.xe2x80x99 FIG. 8 is a diagram for explaining a conventional screen dividing method. As for implementation, it is constructed that Four graphics adapters 201 to 204 are installed at an adapter slot of PC or a work station (WS), and each of the graphics adapter 201 to 204 is assigned to corresponding one of sub-screens that are divided areas of the screen 205, 205a to 205d. To be more specific, each of the graphics adapters 201 to 204 is allowed to be assigned symmetrically to the corresponding one of the divided areas having the same shape, and the screen 205 is divided crosswise. The sub-screens 205a to 205d, each of which is the divided area, are driven so as to create an image by the corresponding graphics adapters 201 to 204. 205a to 205d, the divided areas of the screen 205, have a size, which is a proper scale for the graphics adapters 201 to 204 to create an image.
With respect to a size of the whole screen of the foregoing ultra-high resolution display, the ones having aspect ratios, that is, ratios of the length of the screen to the width thereof 4:3 or 5:4, such as QXGA (2048xc3x971536 dots) and QSXGA (2560xc3x972048 dots), have been the main stream. However, with the diffusion of high definition televisions (HDTV) (and the like), displays and graphics adapters, which have a new aspect ratio such as an aspect ratio in which 1920 dots in the horizontal direction and 1200 dots in the vertical direction are arranged, come to appear. When this display for use in the HDTV is displayed using a plurality of graphics adapters for a high resolution by the screen dividing method, it is impossible to effectively use a frame buffer in each graphics adapter, because a size of whole screen is not equal to an integral multiple of a size of the sub-screen, which is a proper scale for one graphics adapter to create an image.
FIG. 9 is a diagram for explaining the case where a size of the sub-screen, which is a proper scale for one graphics adapter to create an image, is not equal to an integral multiple of a size of the whole screen. In FIG. 9, illustrated is a case where four graphics adapters, each of which includes 1280 dots horizontally and 1024 dots vertically, are used, and an image is displayed on a display (portion indicated by slanted lines) including 1920 dots horizontally and 1200 dots vertically. In this case, since the size of the display is larger than that of one graphics adapter, in other words, since one graphics adapter is narrower than the display (portions indicated by slated lines) both by length and by width, four graphics adapters are necessary as shown in FIG. 9. For this reason, as can be understood from FIG. 9, a useless memory area other than the portion indicated by slanted lines is very large, and hence it was impossible to effectively use the system.
Work stations comprising only one extension slot showing a fast transfer rate and a large bus width in addition to a standard slot can be recently found. In these work stations, for example, one high speed graphics adapter using AGP (Accelerated Graphics Port) and graphics adapters using a PCI bus (Peripheral Component Interconnect bus) bus are allowed to be mixedly present. When it is intended to use a plurality of graphics adapters, the graphics adapters using the PCI bus are used in many cases for the reason that as to the AGP, only one port can be used for the system. However, though it is tried to increase a processing speed by inserting one graphics adapter among the four graphics adapters in the extension slot, the processing speed cannot be increased because the processing speed is ruled by other three graphics adapters. Accordingly, it is impossible to improve performance of the whole of the system.
The present invention is invented to solve the above-described technical problems. The object of the present invention is to provide a monitor system adopting an excellent screen dividing method from a viewpoint of performance and flexibility in a display system using a plural of graphics adapters.
Another object of the present invention is to effectively use a frame buffer of a graphics adapter by reducing a useless memory area, even when an aspect ratio of the graphics adapter and an aspect ratio of a display differ from each other.
To achieve the foregoing object, in the monitor system of the present invention, when screens having different aspect ratios are supported by an existing graphics adapter or when a large screen is supported by a plurality of graphics adapters, an area for which each of graphics adapters can create an image (develop) is divided furthermore into a plurality of divided areas, image data divided by each graphics adapter in accordance with a specified assignment is developed, and the developed image data is reconstructed on a display side. Thus, loads are distributed to each graphics adapter. Therefore, the monitor system to which the present invention is applied comprises a display device having a screen for displaying an image, in which its display area is virtually divided into a plurality of divided areas; and a plurality of graphics adapters, each of which develops image data for corresponding one of the divided areas, wherein each divided area of the screen in the display device is obtained by further dividing an area for which one graphics adapter can create an image.
In such construction, the area for which each graphics adapter can create an image can be characterized by making it smaller than an area that can be displayed by the screen. The display device reconstructs a screen from the image data output from the graphics adapters based on assignment information for the respective divided areas. With such construction, a correct picture can be displayed from divided image data assigned based on characteristics of an application and performance of the system and the graphics adapter.
Furthermore, in the monitor system of the present invention, a high performance graphics adapter is assigned to a divided area having a heavy load on the screen. Thus, it is preferable that performance of the whole of the system can be improved. For example, when the monitor system is constructed so that a graphics adapter using a high performance AGP takes charge of image creation in a central portion of the screen, an image creation speed can be increased even when an application in which loads concentrate in the central portion like a system of, for example, CAD is executed.
The plurality of graphics adapters are assigned to the respective divided areas scattered on the screen to create images on the respective divided areas. Even when the plurality of graphics adapters having the same performance are used, it is possible by the distribution of the loads to cope with a problem in which the image creation speed is slowed down by a graphics adapter having the heaviest load.
When the present invention is comprehended from another point of view, a monitor system comprises: a display device including a screen for displaying an image with a resolution of a first aspect ratio; and a plurality of graphics adapters, each having an area with a resolution of a second aspect ratio which is different from the first aspect ratio, for which image creation can be performed and each supplying, to the display device, image data corresponding to a resolution lower than that of the first aspect ratio of the screen, wherein the image data supplied from each of the graphics adapters divides the area with the resolution of the second aspect ratio, for which an image creation can be performed, into areas having a predetermined size, and undergoes a clipping processing; and the display device reconstructs the image data supplied from the plurality of graphics adapters, and outputs the image data to the screen with the resolution of the first aspect ratio. The aspect ration can be defined generally as a ratio of a lengthwise length to a crosswise length of an image.
The image data supplied from the graphics adapters is formed based on image creation assignment for divided areas obtained by virtually dividing the screen. The display device reads out the image data of the divided areas supplied from the plurality of graphics adapters in turn based on information of the image creation assignment, the image data being subjected to the clipping processing, and reconstructs the image data. This clipping processing is generally defined as an operation to cut off image data corresponding to portions of a screen other than those taken charge of by one of the graphics adapters. The image creation assignment is the one for determining which graphics adapter takes charge of the image creation for a certain area of the screen.
When the present invention is comprehended from the display device side, in the present invention, a reconstruction section is provided in the display device, and the image data, which has a size obtained by further dividing an area for which the graphics adapter can display an image, is read out in turn so that a correct picture is formed. This makes it possible to display an image on the ultra-high resolution display and the image on a display having a different aspect ratio. Specifically, a display device to which the present invention is applied comprises: a frame buffer for storing divided image data received from a plurality of graphics adapters capable of creating an image with a low resolution; a reconstruction section for reading out the divided image data stored in the frame buffer in turn based on a predetermined assignment, and forming display data; and a high resolution screen for displaying an image based on the display data formed by the reconstruction section, wherein the divided image data stored in said frame buffer is formed by further dividing the data of an area having a proper size which is a proper scale for a plurality of graphics adapters to create an image. Here, the high resolution screen is used as a display area an aspect ratio different from that of an area having a proper size which is a proper scale for a plurality of graphics adapters to create an image.
The present invention is directed to a method of displaying an image on a large screen by use of a plurality of graphics adapters, which comprises the steps of: forming divided image data from the image data to be displayed having a size obtained by further dividing an area which said graphics adapters can develop; reading out the divided image data developed into the graphics adapters in a predetermined order and reconstructing the image data; and displaying an image on the screen based on the image data reconstructed.
Assignments of the divided image data to the graphics adapters are performed based on assignment information indicating which portion of the screen is taken charge of by a specific graphics adapter among the graphics adapters. The assignment information complies with assignment used when the divided image data is assigned to a plurality of graphics adapters to be developed in them. The present invention may be constructed so that the assignment information is transmitted to the display device along with the image data. Moreover, the present invention can be constructed so that the assignment information is determined by circuits previously fixed. Specifically, a reconstruction of the image data is read out in a predetermined order based on the assignment information. This makes it possible to display the image data as a correct picture even when the image data is randomly divided in accordance with characteristics of the application. With respect to the divided image data, an area which can be developed by the graphics adapter is divided into different sizes or an even size.
On the other hand, when the present invention is comprehended from another point of view, an image display method to display an image on a high resolution screen of a first aspect ratio, by use of a plurality of low resolution graphics adapters, each being capable of displaying an image having a second aspect ratio different from the first aspect ratio, which comprises the steps of: dividing image data to be displayed to form divided image data in a size obtained by dividing the image displayed by each graphics adapter into a plurality of areas; assigning the divided image data formed to each of the low resolution graphics adapters; reading out the divided image data assigned to each of said low resolution graphics adapters in an order to create a correct image on the high resolution screen, thus reconstructing the image data; and displaying the image data reconstructed on the high resolution screen. The reconstruction of the image data is to read out the divided image data in order based on assignment information to the low resolution graphics adapters. The assignments of the divided image data are determined in consideration of a degree of a load required for displaying the image data. This makes it possible to apply difference of capabilities among the graphics adapters to an unevenness of loads of the image data, and to improve the image creation performance by distributing the loads, thus improving performance of the whole of the system.